Rails installation and setup - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the first step to install Ruby on Rails?

Install Ruby on your computer first because Rails is a Ruby framework. You can download Ruby from the official website or use a version manager like rbenv or RVM.

beginner

How do you install Rails after Ruby is installed?

Use the command gem install rails in your terminal. This downloads and installs the Rails framework on your system.

beginner

What command creates a new Rails project?

Use rails new project_name. This sets up a new folder with all the files and folders Rails needs to start your app.

intermediate

Why do you run bundle install after creating a new Rails app?

It installs all the Ruby gems (libraries) your app needs, as listed in the Gemfile. This makes sure your app has all the tools it requires.

beginner

How do you start the Rails server to see your app in a browser?

Run rails server or rails s in your project folder. Then open http://localhost:3000 in your browser to see your app running.

Which command installs the Rails framework?

A gem install rails

B rails new

C bundle install

D ruby install rails

The command gem install rails installs the Rails framework after Ruby is installed.

What does rails new myapp do?

A Starts the Rails server

B Updates Rails to the latest version

C Creates a new Rails project named myapp

D Installs Ruby

The command rails new myapp creates a new Rails project folder called myapp with all necessary files.

Why is Ruby needed before installing Rails?

A Rails is a Ruby framework and needs Ruby to run

B Ruby installs Rails automatically

C Ruby is a database

D Ruby is a web server

Rails is built with Ruby, so Ruby must be installed first for Rails to work.

What is the purpose of bundle install?

A To start the Rails server

B To install all gems listed in the Gemfile

C To create a new Rails app

D To uninstall Rails

bundle install installs all the Ruby libraries your app needs as specified in the Gemfile.

After running rails server, where do you go to see your app?

A http://127.0.0.1:5000

B http://railsapp.com

C http://localhost:8080

D http://localhost:3000

The Rails server runs on port 3000 by default, so you visit http://localhost:3000 to see your app.

Explain the steps to install and set up a new Rails application from scratch.

Think about what you need before Rails, how to get Rails, and how to start your app.

Describe what happens when you run the command 'rails new project_name'.

Imagine setting up a new workspace for your app.

Practice

1. What is the main purpose of running gem install rails in your terminal?

easy

A. To install the Rails framework on your computer

B. To create a new Rails project

C. To start the Rails server

D. To update Ruby to the latest version

Solution

1. Step 1: Understand the command gem install rails

   This command uses Ruby's package manager (gem) to install the Rails framework on your system.

2. Step 2: Differentiate from other commands

   Creating a project uses rails new, and starting the server uses rails server. Updating Ruby is separate.

3. Final Answer:

   To install the Rails framework on your computer -> Option A

4. Quick Check:

   Install Rails = gem install rails [OK]

Hint: Install Rails with gem install rails command [OK]

Common Mistakes:

• Confusing installation with project creation
• Trying to start server before installing Rails
• Mixing Ruby update with Rails installation

2. Which command correctly creates a new Rails application named myapp?

easy

A. rails create myapp

B. rails new myapp

C. gem new myapp

D. rails start myapp

Solution

1. Step 1: Identify the correct Rails command for project creation

   The command to create a new Rails app is rails new appname.

2. Step 2: Check each option

   rails create myapp uses 'create' which is incorrect. gem new myapp uses 'gem' which manages packages, not projects. rails start myapp uses 'start' which is for running the server.

3. Final Answer:

   rails new myapp -> Option B

4. Quick Check:

   Create app = rails new [OK]

Hint: Use rails new appname to create a project [OK]

Common Mistakes:

• Using 'rails create' instead of 'rails new'
• Confusing gem commands with Rails commands
• Trying to start app with wrong command

3. After running rails new blog and then cd blog, what happens when you run rails server?

medium

A. Starts a web server accessible at http://localhost:3000

B. Creates a new Rails project named blog

C. Installs Rails gems needed for the project

D. Displays an error because the server command is invalid

Solution

1. Step 1: Understand the rails server command

   This command starts the Rails web server so you can view your app in a browser.

2. Step 2: Confirm the server address

   By default, the server runs on port 3000 and is accessible at http://localhost:3000.

3. Final Answer:

   Starts a web server accessible at http://localhost:3000 -> Option A

4. Quick Check:

   rails server = start web server [OK]

Hint: rails server runs app at localhost:3000 [OK]

Common Mistakes:

• Thinking rails server creates a project
• Expecting gem installation during server start
• Assuming server command is invalid

4. You ran rails new myapp but got an error saying 'command not found: rails'. What is the most likely cause?

medium

A. Ruby is not installed on your system

B. You forgot to create the project folder manually

C. Rails gem is not installed or not in your PATH

D. You need to run rails server first

Solution

1. Step 1: Analyze the error 'command not found: rails'

   This error means the system cannot find the rails command, usually because the Rails gem is missing or not accessible.

2. Step 2: Check other options

   Creating a folder manually is not needed; Ruby missing would cause a different error; running server first is unrelated.

3. Final Answer:

   Rails gem is not installed or not in your PATH -> Option C

4. Quick Check:

   Missing rails gem = command not found [OK]

Hint: Install Rails gem before using rails commands [OK]

Common Mistakes:

• Assuming folder must be created manually
• Confusing Ruby absence with Rails command error
• Trying to run server before project exists

5. You want to create a new Rails app but skip installing all default gems to speed up setup. Which command should you use?

hard

A. rails new appname --skip-install

B. rails new appname --no-gems

C. gem install rails --skip-defaults

D. rails new appname --skip-bundle

Solution

1. Step 1: Identify the option to skip gem installation during project creation

   The --skip-bundle flag tells Rails to create the app without running bundle install which installs gems.

2. Step 2: Evaluate other options

   rails new appname --no-gems is invalid syntax, gem install rails --skip-defaults misuses gem install, rails new appname --skip-install is not a recognized flag.

3. Final Answer:

   rails new appname --skip-bundle -> Option D

4. Quick Check:

   Skip gem install = --skip-bundle [OK]

Hint: Use --skip-bundle to skip gem install on new app [OK]

Common Mistakes:

• Using invalid flags like --no-gems or --skip-install
• Trying to skip gem install with gem install command
• Confusing bundle install with rails new options